A surface acoustic wave (SAW) sensor is a device that may be used to analyze a particular target material in a sample by using a SAW. A SAW is an acoustic wave that travels along the surface of a material, and can be generated when particles in the material vibrate due to an external thermal, mechanical, or electrical force. A SAW exhibits vibration energy that is mostly concentrated on the surface of the material. The movement of a SAW in a material is affected by one or more properties of the material. A SAW sensor can be used to analyze a target material by sensing a change in a SAW caused by a change in a property of the material. For example, a change in intensity, phase, or central wavelength of the SAW may indicate the presence of a particular target material.
A conventional SAW sensor may include a substrate formed of a piezoelectric material, an input interdigital transducer (IDT) that generates a SAW by applying an electrical stimulus to the substrate, and an output IDT that receives the SAW. In the SAW sensor, a portion between the input IDT and the output IDT in which the SAW travels is generally referred to as a delay line. A receptor having a specific binding with a desired particular target material may be disposed on a path on which the SAW travels on the substrate, for example, in the delay line.
When a SAW is generated in the SAW sensor having the above structure and a sample including a target material is applied to the SAW sensor, the target material may combined with the receptor and change an intensity, phase, or central wavelength of the SAW that is received from the output IDT. Thus, by sensing a change in the SAW, it may be determined whether the target material exists in the sample, and the content of the target material in the sample may be precisely measured.
A SAW array sensor may be configured by arranging a plurality of SAW sensors on one substrate. By using a SAW array sensor, various types of receptors may be disposed on the substrate, so as to analyze various components of the sample at one time. The SAW array sensor can suppress cross-talk that is generated due to a reflected wave generated in adjacent delay lines, and simultaneously, the size of the SAW array sensor may be reduced.